<VV> "Clunk" when shifting into gear

[Edelstein and Payne]

Folks,

    My 21 year old son uses a daily driver 65 coupe, 110 powerglide.  We've kept it alive for a couple of years while we're finishing the 65 Monza hotrod.  For some time it has made a "clunk" sound when you shift it into drive or reverse.  It is now starting to get louder and I'm concerned that at some point the car may not move.  I have checked the u-joints and they don't seem to have a lot of play.  The motor and transmission mounts also look okay and are not loose.  Is this likely to be something in the hubs/wheel bearings or is it the differential???

    Thanks for your help.

               Travis Payne     65 Monza coupe
               Raleigh, NC      65 500 coupe